Australian personal number plates- need help from an Aussie

[TopTrump]

My brother is selling his car in Australia (Melborne) and has private plates on his car. He no longer lives there and is back in the UK. Are his options;

1./ sell the car with the plates
2./ sell the plates separately to the car

In any instance does he physically have to be in Australia to do this? Or can any paperwork be Fedexed to him the UK? I'm obviously trying to save him an airfare and his mate is selling on his behalf.

Thanks

[TopTrump]

Thanks Jader- appreciate the response. It is a Landcruiser